Having difficulty cutting the plastic? Try blowing hot air from a hairdryer on the area where you plan to cut. This softens the plastic and makes it much easier to cut through.

Consider surrounding the shelter with bails of straw. Did you know that straw is a fabulously efficient insulator? Homes insulated with 18" wide bails of straw could save 75% on heating & cooling costs. Just think what that could do for your cats!

Place shelters where they will be protected from wind and snow drifts -- particularly those without protective flaps over the door(s) -- otherwise snow could blow in and bury/trap the cats. If there are fixed objects, such as buildings in your feral cat shelter area, pay attention to the way the winds tend to circulate, and place the shelters where there is the least amount of blowing & drifting snow. This could be a lifesaver, particularly for those who endure extreme winter weather, in which roads may be impassable for 1-2 days.

Depending on predators and other animals/hazards in your area, some cats may not use shelters unless there are two exits -- one for them to sneak out should another unwanted animal enter. Consider an emergency exit with a flap that opens from the inside only.